<!DOCTYPE html>
<html>
<head>
	<meta charset="utf-8">
	<meta name="viewport" content="width=device-width, initial-scale=1">
	<title></title>
</head>
<body>
	<script type="text/javascript">
		let arr = [1, 3, 4, 5, 7]
		// 数组[数组.length] = "" 恒定往数组最后添加一个数据
		arr[arr.lenght] = "hi"
		console.log(arr)

		//数组的取赋值
		//取值
		console.log(arr[2]) //4
		//赋值
		arr[2] = "hello"
		console.log(arr)
	</script>
</body>
</html>